What has been going on? Fracking of natural gas in the U. But new studies are raising serious questions about that. Researchers are now saying say that, globally at least, the increase in recent years is due to the activities of microbes in wetlands, rice paddies, and the guts of ruminants.
But he says his research shows that the increase is dominated by microbial emissions , particularly from the tropics. Yet that hardly exonerates gas fracking. It turns out that, all along, natural gas and other fossil fuels have been a bigger source of methane emissions than the industry has declared in submissions to governments and the UN. The companies may not have been deliberately lying; but the new studies prove that they were certainly and comprehensively wrong.
The new data come from combining two approaches to unraveling the methane riddle. First is a new database of isotopic analyses of methane in the air. This analysis can distinguish between methane coming from the three main categories of sources: the output of microbes living in anoxic environments such as wetlands, landfills, and the stomachs and butts of ruminants; fossil methane in gas, coal, and other underground fuel reserves that is released as those reserves are exploited; and the burning of vegetation like forests, bush, and crop residues.
Methane molecules from each of these sources have a characteristic ratio of two carbon isotopes, carbon and carbon Microbes fractionate the isotopes, increasing the proportion of carbon compared to fossil methane.
Yet methane from burning trees or crop residues has a higher proportion of carbon, because photosynthesis favors that isotope. Second, satellite observations of methane concentrations in the air are allowing researchers to accurately identify the regions of the world from which increases in emissions are occurring. As the two approaches are combined, a previously fuzzy image of methane sources is becoming dramatically clearer. He developed a global database of isotopic measurements taken all over the world in the past three decades and analyzed the trends.
First, the recent methane surge into the atmosphere is due not to the rising fossil-fuel emissions, but rather to an unexpected surge in microbial sources. Second, fossil-fuel sources are — and have been for at least some decades — almost twice as big as previous estimates, whereas microbial sources are about a quarter less.
Microbial methane still accounts for the majority of emissions, totalling almost million tons a year, but fossil-fuel emissions are much more significant than previously thought, at about million tons. Methane lasts in the atmosphere only for about 12 years, much less than CO2; but while there, it packs a punch.
Measured over a century, a molecule of methane warms the planet roughly 30 times more than CO2. The findings from the latest methane studies have caught scientists by surprise.
But they are backed up by other recent research. And he reached a similar conclusion. Anna Robertson U. We partnered with Google Earth Outreach to get utilities to find and fix methane leaks under city streets photo credit: Mathew Grimm. Until recently, little was known about where leaks were occurring, or the best way to fix them. In , we kicked off a research series to better pinpoint leaks — and to find solutions. It is the largest body of peer-reviewed research on the issue.
A synthesis of the research found that the U. The volume represents enough natural gas to fuel 10 million homes. Today we have much better data on where the methane is coming from and how to prevent it. Ground-based measurement tools along with a growing number of satellites — including one being launched by our MethaneSAT subsidiary — are making it faster and cheaper than ever to locate, measure and reduce emissions.
Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals.
Human activities are altering the carbon cycle—both by adding more CO 2 to the atmosphere, and by influencing the ability of natural sinks, like forests and soils, to remove and store CO 2 from the atmosphere. While CO 2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.
Carbon dioxide is constantly being exchanged among the atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals. However, emissions and removal of CO 2 by these natural processes tend to balance, absent anthropogenic impacts. Since the Industrial Revolution began around , human activities have contributed substantially to climate change by adding CO 2 and other heat-trapping gases to the atmosphere.
In the United States, since , the management of forests and other land e. This carbon sink offset is about 12 percent of total emissions in and is discussed in more detail in the Land Use, Land-Use Change, and Forestry section. To find out more about the role of CO 2 in warming the atmosphere and its sources, visit the Climate Change Indicators page. Carbon dioxide emissions in the United States increased by about 3 percent between and Since the combustion of fossil fuel is the largest source of greenhouse gas emissions in the United States, changes in emissions from fossil fuel combustion have historically been the dominant factor affecting total U.
Changes in CO 2 emissions from fossil fuel combustion are influenced by many long-term and short-term factors, including population growth, economic growth, changing energy prices, new technologies, changing behavior, and seasonal temperatures. Between and , the increase in CO 2 emissions corresponded with increased energy use by an expanding economy and population, including overall growth in emissions from increased demand for travel.
The most effective way to reduce CO 2 emissions is to reduce fossil fuel consumption. Many strategies for reducing CO 2 emissions from energy are cross-cutting and apply to homes, businesses, industry, and transportation.
Improving the insulation of buildings, traveling in more fuel-efficient vehicles, and using more efficient electrical appliances are all ways to reduce energy use, and thus CO 2 emissions. Reducing personal energy use by turning off lights and electronics when not in use reduces electricity demand. Reducing distance traveled in vehicles reduces petroleum consumption. Both are ways to reduce energy CO 2 emissions through conservation. Producing more energy from renewable sources and using fuels with lower carbon contents are ways to reduce carbon emissions.
Carbon dioxide capture and sequestration is a set of technologies that can potentially greatly reduce CO 2 emissions from new and existing coal- and gas-fired power plants, industrial processes, and other stationary sources of CO 2. For example, capturing CO 2 from the stacks of a coal-fired power plant before it enters the atmosphere, transporting the CO 2 via pipeline, and injecting the CO 2 deep underground at a carefully selected and suitable subsurface geologic formation, such as a nearby abandoned oil field, where it is securely stored.
Some of the excess carbon dioxide will be absorbed quickly for example, by the ocean surface , but some will remain in the atmosphere for thousands of years, due in part to the very slow process by which carbon is transferred to ocean sediments. Qin, G. Plattner, M. Tignor, S. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. Midgley eds. In , methane CH 4 accounted for about 10 percent of all U. Human activities emitting methane include leaks from natural gas systems and the raising of livestock.
Methane is also emitted by natural sources such as natural wetlands. In addition, natural processes in soil and chemical reactions in the atmosphere help remove CH 4 from the atmosphere. Methane's lifetime in the atmosphere is much shorter than carbon dioxide CO 2 , but CH 4 is more efficient at trapping radiation than CO 2. Pound for pound, the comparative impact of CH 4 is 25 times greater than CO 2 over a year period.
Globally, percent of total CH 4 emissions come from human activities. Methane is also emitted from a number of natural sources. Natural wetlands are the largest source, emitting CH 4 from bacteria that decompose organic materials in the absence of oxygen.
Smaller sources include termites, oceans, sediments, volcanoes, and wildfires. To find out more about the role of CH 4 in warming the atmosphere and its sources, visit the Climate Change Indicators page. Methane emissions in the United States decreased by 15 percent between and During this time period, emissions increased from sources associated with agricultural activities, while emissions decreased from sources associated with landfills, coal mining, and from natural gas and petroleum systems.
There are a number of ways to reduce CH 4 emissions.
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